1. Field of the Invention
The present invention relates to disc players that play back discs, each including music files in a plurality of folders and managing the music files for every folder, and, more particularly, to a disc player capable of playing back all music files in each folder.
2. Description of the Related Art
Data is recorded on a CD-R/RW medium in a disc-at-once mode, a session-at-once mode, a track-at-once mode, or the like.
In the disc-at-once mode, the lead-in, data, and the lead-out are written as one continuous portion on a disc, without any interruptions, until the entire data set is transferred to the disc and additional data cannot be written on the disc. Compact disc digital audio (CD-DA) adopts this mode.
In the session-at-once mode, the lead-in, data, and the lead-out of a session are written as one continuous portion on a disc and additional data can be written on the disc. The area between the lead-in and the lead-out, inclusively, is referred to as the session.
In the track-at-once mode, a session is written in a number of tracks and additional data can be written on the disc. After the data is written on all tracks, the lead-in and the lead-out of the corresponding session are written. When the data is written on a disc in the track-at-once mode, the lead-in LI, data (program area) P, and the lead-out LO respectively have a seam at the head thereof and a seam at the trail thereof, as shown in FIG. 4. The head seam is referred to as a run-in and the trail seam is referred to as a run-out.
Writing data in sessions in the track-at-once mode produces a multi-session disc. FIG. 5 shows the structure of a multi-session disc. In the multi-session disc, each time a session is appended to the disc, the lead-in areas LI1 to LI3 are respectively provided at the heads of the program areas P1, P2, and P3 and the lead-out areas LO1 to LO3 are respectively provided at the trails thereof Volume descriptors, path tables, and so on (described below) of the sessions additionally written and of the sessions already recorded are written in the lead-in areas LI1 to LI3. Accordingly, reading the lead-in area of the last session reveals the file structure of the entire disc volume. Compressed music data of, for example, MP3 (MPEG-1 audio layer 3) and WMA (Windows media audio) can be written in the sessions of the discs shown in FIGS. 4 and 5 in a CD-ROM (compact disc read only) format.
FIG. 6 shows the structure of a sector in a CD-ROM mode 1. In the CD-ROM mode 1, a sector has a size of 2,352 (=24×98) bytes. One sector contains 98 frames (one frame has a size of 24 bytes) and includes the following:
(1) synchronization (synchronization signal) data SKD of 12 bytes
(2) a header HDD of four bytes
(3) user data USD of 2,048 bytes
(4) ancillary data EDCC of 288 bytes for error correction and detection.
Of the four bytes of the header HDD, three bytes (MIN/SEC/SECTOR) contain address information and the remaining one byte contains mode information indicating the type of data. The address information basically includes the same data as a sub-code Q channel and is represented as minute/second/sector format, like the sub-code of the CD-DA. Also, the synchronization signal, the sub-code, and an error correcting code (CIRC) are appended to each frame, as in the signal unit format in the CD-DA.
When the data is written on the CD-ROM, the data is divided into sectors and the sub-code and the CIRC are appended, as in the CD-DA. After the data is modulated by EFM (eight-to-fourteen modulation), it is written on the CD-ROM. The data is read out from the CD-ROM for every sector with the sub-code (the absolute address of the Q channel).
As described above, the data on the CD-ROM is divided into logical sectors, each having a size of 2,048 bytes and containing 2n logical blocks (it is often the case that n=0). A volume has a system area that uses the first 16 sectors (logical sector numbers from 0 to 15) and a data area. In the case of a volume conforming to the ISO9660 standards, the data area has a volume descriptor BDC, a path table PTH, directories DRT, and data DT, as shown in FIG. 7A. Volume descriptors include a primary volume descriptor, a supplementary volume descriptor, a volume partition descriptor, and so on.
The primary volume descriptor contains information such as a volume identifier A0, logical block size A1, path table size A2 for determining a file structure (FIG. 8), and path table location A3, as shown in FIG. 7B.
The path table contains information such as a directory identifier (folder name) B1, a parent directory number B2, and record location (extent location) B3 of a directory (for example, a file) included in a folder (directory), as shown in FIG. 7C. A plurality of path tables of directories that has a root directory as the parent directory is continuously written on the CD-ROM.
The directory contains information such as a file identifier C1, starting address of file (extent location) C2, file flag C3, and data size of file C4, as shown in FIG. 7D. Directory records of a plurality of files in a directory (folder) are continuously written on the CD-ROM.
FIG. 8 shows an exemplary file structure. The root directory has a plurality of directories (folders: R&B, ROCK, JAZZ, POPS, . . . ), the folder ROCK has subfolders ROCKMAN and ROCKWOMAN, and the folder R&B has a plurality of MP3 files (MP3 music file) RB-1, RB-2, . . . . Similarly, other folders have some MP3 music files. This file structure can be determined by analysis of the primary volume descriptor BDC, the path table PTH, and the directories DRT that are described above.
Heretofore, the playback of discs has been controlled for every disc. However, such playback control has disadvantages in the playback of the disc that has folders including music files for the following reason.
A maximum of 255 music files can be written on a CD-R/RW medium in the CD-ROM format with a compression technique such as the MP3. However, more than 255 music files can be written depending on the capacity of a recording medium or the specifications of writing software. As described above, in the CD-ROM format, the recording structure of music data on a disc can be described with a primary volume descriptor, a path table, and directories. For example, when a user prepares a music disc, a folder is created for every category (R&B, ROCK, JAZZ, POPS, . . . ), as shown in FIG. 8, and music files corresponding to each category are added to each folder. This file structure is described with the primary volume descriptor, the path table, and the directories. However, when the music discs are played back with the conventional disc-based playback mode, it is not possible to just play back the music files from one category, for example, ROCK or JAZZ.